Steve,
Without CLI access your going to struggle.
Q : How far does the traceroute get, from the send
node ?
try rfc 792 ICMP
http://www.landfield.com/rfcs/rfc792.html
>> SNIP from RFC 792
If a host reassembling a fragmented datagram
cannot complete the
reassembly due to missing fragments within its
time limit it
discards the datagram, and it may send a time
exceeded message.
If fragment zero is not available then no time
exceeded need be
sent at all.
Good luck,
Phil.
--- "Donohue, Steve" <[EMAIL PROTECTED]> wrote:
> Good Afternoon All,
>
> I am currently trying to resolve an issue where we
> are having trouble
> sending data across a tunnel running GRE encryption.
> With this encryption
> employed the MTU size allowed is decreased to 1476.
> When we attempt to send
> traffic (email, ftp, etc...) through the tunnel, we
> are finding that it does
> not work.
>
> My sniffer trace is showing that the frames being
> sent are setting the DF
> bit, which I would expect. I would then expect that
> if the router is unable
> to send the packet, it would drop it and return an
> ICMP message back to the
> source telling it to decrease the packet size and
> try it again. I am not
> seeing any of these messages.
>
> We are running HSRP on the ethernet interfaces that
> connect to my LAN. I
> believe we are running a 12.0 IOS release, although
> I am not sure of the
> actual version.
>
> Does anyone have any ideas why this might be
> happening? I am trying to
> resolve this issue while having no CLI access to the
> routers. I have been
> informed by the controlling body that there are no
> access lists prohibiting
> ICMP messages from being sent, and there are no
> firewall rules in place that
> would be dropping the ICMP messages.
>
> Any and all explanations of possible
> causes/resolutions would be
> appreciated.
>
> Steve D.
>
>
>
>
>
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